It is a common practice for such items as credit cards, driver's licence, and the like, to be kept in a wallet. Often, the wallet is so constructed as to provide a separate respective pocket for each item. Typically, a wallet might contain 8 or 10 such pockets.
It is all too easy for the owner of the wallet, after making a purchase with a credit card for example, to forget to return the card to its compartment in the wallet. He might pick up the card and place the card loose in another pocket, or, worse still, he might leave the card behind.
The aim of the invention is to provide a device which will alert the owner of the wallet to the fact that one of the cards has not been properly replaced in its compartment.